Postganglionic Sudomotor Dysfunction and Brain Glucose Hypometabolism in Patients with Multiple System Atrophy

Area of Science:

• Neurology
• Autonomic Neuroscience

Background:

• Sudomotor dysfunction is a frequent complication in multiple system atrophy (MSA).
• This dysfunction stems from the degeneration of sympathetic neurons and postganglionic fibers, measurable via quantitative sudomotor axon reflex testing (QSART).

Purpose of the Study:

• To investigate the association between abnormal QSART responses and disease severity in patients with MSA.
• To explore the relationship between sudomotor function, overall disease burden, and neuroimaging findings.

Main Methods:

• A retrospective study included probable MSA patients who underwent 18F-FDG-PET/CT and autonomic function tests.
• Autonomic function tests were scored for sudomotor, cardiovagal, and adrenergic functions, with sudomotor function assessed by QSART.
• Disease severity was evaluated using the Unified Multiple System Atrophy Rating Scale (UMSARS) Parts I, II, and I+II.

Main Results:

• Abnormal QSART results were observed in 62.2% of 74 MSA patients.
• Patients with abnormal QSART exhibited significantly higher UMSARS Part I+II scores.
• Regression analysis revealed significant associations between UMSARS Part I and II scores and the sudomotor sub-score, indicating a link between sudomotor function and disease severity.
• Abnormal QSART correlated with reduced metabolic activity in the cerebellum (MSA-P) and basal ganglia (MSA-C) on 18F-FDG-PET/CT.

Conclusions:

• Postganglionic sudomotor dysfunction in MSA patients is associated with greater disease severity.
• These patients may also exhibit a more significant neuropathological burden compared to those without sudomotor dysfunction.